Something is wrong in # 3 in the procedure. The non-distributor side is a
regular hot wire when the ignition is on and on the key it will be the same.
You`ll probably have to run the wire from the distributor side of the coil (for
getting the ignition-impulses) to the tach and from there, probably to the
ground - I can`t be sure, there are several different systems, depending on the
brand. What the tach does is reacting on the discharge of the power-build up in
the coil, thats when the points open.
Good luck
Chris
Greg MAHNEY wrote:
> Thanks to all those who have given me advice on this matter. I'll try them
> out over the weekend and let you know how I go.
>
> The car is Positive Earth so I can rule out that one, sorry I didn't
> mention it in my original post.
>
> One thing I'll try is to fabricate a U shaped piece of metal to place on
> top of the plastic encased wire between the plastic and the nut - right?
> I'll try that first.
>
> Also, can anyone comment on the likely effectiveness of the following TEST
> procedure:
>
> 1. Make sure the Tach has got a good earth
>
> 2. Check the Green wire to the spade connector is a power wire
>
> 3. Run a piece of wire from the SW side of the coil (the non-distributor
> side) to the small threaded post on the back of the tach, form that wire
> into a loop around the post and either hold it there or hold it in place
> with a washer and nut. Run the other end of the wire to the connector on
> the key.
>
> 4. start her up and see.
>
> 5. If it doesn't work, reverse the loop, recheck all other conections and
> try again
>
> Have I got it right? Anthing I'm forgetting?
>
> Thanks again to all those who have offered support - it's very dull
> (relatively speaking) driving a sports car with no tacho.
>
> Cheers
>
> Greg
>
> >Chris Kotting wrote:
> >
> >It's been awhile since I've done one but I think I remember going inside
> >and
> >having to snip a resistor lead and resolder on another terminal but
> >can't give more details.
> >I'm sure someone else can confirm whether you need to go inside the tach
> >itself.
> >I also remember it being printed in an earlier Moss Motors cataogue
> >years ago as a
> >techtip!
> >Regards
> >Alan
> >
> >> Daryl's right.
> >>
> >> As I recall the change is simply to mount the loop the other way
> >> around.
> >> (I.E. Looking at the back of the tach, put a masking tape flag on the
> >> part
> >> of the wire that leaves the loop to the right. Turn the loop around
> >> so
> >> that the tape flag is on the left.)
> >>
> >> Chris Kotting
> >> ckotting@iwaynet.net
> >>
> >> On Wednesday, February 11, 1998 11:17 PM, Daryl May
> >> [SMTP:mayfam@sprynet.com] wrote:
> >> > Greg,
> >> >
> >> > Is the car still positive earth, or has it been converted to
> >> negative? I
> >> > am positive that a positive earth tacho will only work on a negative
> >>
> >> earth
> >> > car with some wiring changes, which include changing the white wire
> >> loop
> >> in
> >> > some way. Sorry if this sounds negative, but it may explain some of
> >> the
> >> > difficulties (and PO's wiring changes), and perhaps this will need
> >> to be
> >> > considered in the solution?
> >> >
> >> > Daryl
> >> >
> >> >
> >> > ----------
> >> > > From: Greg MAHNEY <mahney@central.murdoch.edu.au>
> >> > > To: spridgets@autox.team.net
> >> > > Subject: Troubles with Tacho
> >> > > Date: Tuesday, February 10, 1998 6:45 PM
> >> > >
> >> > > I'm still trying to get the Tacho (it's an electronic one) on my
> >> Mk 2
> >> > > Sprite to work. It never has worked in the months that I have had
> >> the
> >> > car.
> >> > >
> >> > >
> >> > > Looking under the dash there is a spade connector on the back of
> >> the
> >> > Tacho,
> >> > > and a green wire nearby. I've pushed the green wire onto the
> >> connector
> >> > > (this seems to tie in with the wiring diagram I've got). Apart
> >> from
> >> the
> >> > > instrument light there did not appear to be any other connections
> >> until
> >> I
> >> > > started untangling the mass of wires under there.
> >> > >
> >> > > I then found a white wire which has a loop in it which is totally
> >> > enclosed
> >> > > in a block of opaque nylon. Is this the other wire? Does it
> >> connect
> >> to
> >> > > the other side of the Tacho to the green wire? Is it a case of
> >> putting
> >> > it
> >> > > on that thin threaded post and finding a small nut to secure it?
> >> If
> >> so,
> >> > > there is no obvious electrical contact, does the thing just sense
> >> the
> >> > > electrons whipping past (sorry - I'm a sociologist, not an
> >> engineer:-)
> >> > ) ?
> >> > >
> >> > > As you might expect, I did try connecting it but nothing happened.
> >>
> >> When
> >> > I
> >> > > checked that there is a white wire at the coil, there was (on the
> >> > oppisite
> >> > > terminal to the one which leads to the distributor) but there was
> >> an
> >> > > additional (blue) wire connected next to the white wire. It has
> >> > obviously
> >> > > been added by a previous owner and goes from the coil to thin air
> >> near
> >> > the
> >> > > Tacho. That is to say, it looks to me like someone tried to
> >> replace
> >> the
> >> > > white wire with this blue one. In the interests of
> >> experimentation I
> >> > held
> >> > > that (blue) wire to the thin threaded terminal, but nothing
> >> happened..
> >> > >
> >> > > So far I haven't been able to get the Tach out of the wooden dash
> >> (see
> >> my
> >> > > other post today) so I am keen to test the tacho in situ. Can
> >> anyone
> >> > tell
> >> > > me how to do this please? And/or answer the questions above?
> >> > >
> >> > > I appreciate the help.
> >> > >
> >> > > Greg
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